Willow bark comes from the bark of various species of the willow tree, particularly the Salix genus. It has been used for centuries in traditional medicine due to its natural compounds, including salicin, which the body converts into salicylic acid. This compound is known for its pain-relieving and anti-inflammatory properties. In modern times, willow bark is often marketed as a herbal supplement for conditions like headaches, muscle pain, and arthritis. It is available in various forms, including capsules, teas, and extracts, making it accessible for those seeking natural alternatives to conventional pain relief methods.